System for controlling a central differential of a four-wheel drive motor vehicle

Abstract

A central differential has first and second output members for distributing power of an engine through a transmission to front and rear wheels respectively, and has a third output member for controlling distribution of the power. A first friction clutch is operatively connected to the second and third output members for restricting differential operation of the central differential and for controlling distribution of the power to the front and rear wheels. A second friction clutch is operatively connected to the second output member and either of the front or rear wheels. The first friction clutch is disposed at the innermost position and the second friction clutch is disposed around the first friction clutch so as to effectively transmit and distribute power to each wheel in compact and simple structure.

What is claimed is: 
     
       1. A system for controlling a central differential having an input member operatively connected to a transmission for receiving a power from the transmission a first output member operatively connected to a one side of front and rear wheels for transmitting power of an engine through the transmission to the one side of front and rear wheels, a second output member operatively connected to another side of the front and rear wheels for transmitting power to the another side of the front and rear wheels, and a third output member for controlling distribution of the power to the front and rear wheels, the improvement of the system which comprises: first friction engagement means operatively connected to the second and third output members for restricting differential operation of the central differential and for controlling distribution of the power to the front and rear wheels;   second friction engagement means for connecting the second output member and the one side of the front and rear wheels operatively;   said first friction engagement means being disposed at the innermost position adjacent an extension of an axis of the central differential; and   said second friction engagement means being disposed around said first friction engagement so as to effectively transmit and distribute power to each wheel in compact and simple structure.   
     
     
       2. The system according to claim 1, further comprising braking means disposed around the transmitting means for braking rotation of the first output member of the central differential.   
     
     
       3. The system according to claim 2, wherein the central differential comprises a planetary gear device including a first sun gear operatively connected to an output shaft of the transmission, a carrier operatively connected to the third output member, first and second planetary pinions integral with each other and rotatably supported on the carrier, and a second sun gear connected to the second output member, the first planetary pinion engages with the first sun gear, the second planetary pinion engages with the second sun gear, the carrier is operatively connected to the first output member connected to the one side of the front and rear wheels, the second output member is operatively connected to the another side of the front 2nd rear wheels, and the first and second friction means are fluid operated clutches respectively.   
     
     
       4. The system according to claim 3, wherein each of the fluid operated clutches comprises a plurality of disks mounted on a drive drum and a driven drum, an oil chamber, a piston provided in the oil chamber for engage the disks with each other.   
     
     
       5. The system according to claim 4, wherein the oil chamber is difined by a stationary member and the piston.   
     
     
       6. The system according to claim 4, wherein the diameter of the piston is larger than that of the diameter of the outer side drum.   
     
     
       7. The system according to claim 4, further comprising a lubricating system which is provided for passing lubricating oil from the innermost restricting means to the outermost braking means.   
     
     
       8. The system according to claim 4, wherein the third output member is disposed at the innermost position, the second output member is disposed around the third output member, the third output member has a connecting member which radially and outwardly extends at an inner end of the second output member and is operatively engaged with the carrier.